1. Field of the Invention
The present invention relates to an optical member, a method of manufacturing an optical member, and an image display device. More specifically, the present invention relates to an optical member in which the proportion of a retroreflective area is high when the optical member is observed after light irradiation from a direction which is oblique to a normal direction perpendicular to the optical member, a method of manufacturing the optical member, and an image display device in which the optical member is used.
2. Description of the Related Art
A material having a cholesteric structure has wavelength selective reflecting properties and, due to these properties, has been used as materials for forming various optical members. For example, JP2008-225727A discloses a reflection pattern-printed transparent sheet that is mounted to face a front surface of a medium on which an image can be displayed, the transparent sheet including: a transparent substrate; and a transparent pattern having invisible light reflecting properties that is printed on a surface of the transparent substrate, in which an ink which forms the transparent pattern includes an invisible light reflecting material, the invisible light reflecting material has wavelength selective reflecting properties in an invisible light reflecting wavelength range, and a thickness of the transparent pattern is 6 to 20 μm. In particular, JP2008-225727A describes an aspect where the transparent pattern has a multi-layer structure including a fixed repeating cycle and where the multi-layer structure is formed of a liquid crystal material having a fixed cholesteric structure. In addition, when mounted on an image-displayable device and used in combination with an input terminal (for example, a so-called electronic pen) capable of irradiating and detecting invisible light such as infrared light, the reflection pattern-printed transparent sheet described in JP2008-225727A can be used as a member providing coordinate detecting means which is suitably applicable to a data input system in which data can be handwritten directly on a screen of a display device.